SE468059B - DEVICE FOR GAME ROOM CONTROL OF A GAS TURBINE ENGINE - Google Patents

Abstract

The invention concerns an active clearance control for controlling clearance between a turbine and a casing in a gas turbine aircraft engine. The invention calculates the instantaneous clearance between a turbine casing and a turbine rotor, based on temperature. Two temperatures are involved. First, a steady state temperature (SSTemp) is computed for the rotor and the casing. SSTemp is a predicted, future temperature, which will be attained when the engine reaches steady state operation. Each SSTemp is computed based on presently occurring engine operating conditions, such as selected temperatures, pressures, and rotational speeds. Changes which occur in the SSTemp's indicate the second temperatures, which are the instantaneous temperatures of the casing and rotor. These changes in SSTemp are caused by changes in the present operating conditions, which occur during engine acceleration and deceleration. The instantaneous temperatures indicate the diameters of the casing and the rotor, and thus the instantaneous clearance between them. In another form of the invention, the computed instantaneous clearance is used to control air which is bled from the fan and ducted onto the casing, in order to attain a desired clearance.

Description

468 059 2 is illustrated by the reduction of the spear in the area 61 in Fig. 3. The centrifugal force is quite large, as an example will show.

The centrifugal acceleration is equal to w2r, where w is the angular velocity in radians per second and r is the radius. 11,000 revolutions per minute corresponds to about 175 revolutions per second. The diameter 48 is about ß '0.6 m, the radius is 0.3 m and the centrifugation is (53 x 2 x pi) 2, or 0.38 x 105 m / sec. If this value is divided by the gravitational acceleration, namely 9.8 m / second, a centrifugal force of approximately 37,600 G is obtained.

This large G-value occurs immediately upon acceleration and increases the diameter of the turbine rotor. The actual diameter increase from the basic idle speed to the lift speed may be 0.7 mm (0.028 inches). Therefore, while the diameter of the mantle 39 in Fig. 2 is constantly passing, the elastic growth of the rotor tends to reduce the gap 33 and there is a risk that the bead 36 may come into contact with the mantle 39.

The second factor is the increasing diameter of the mantein 39, which occurs due to the pressure increase of the gas stream 14. The pressure increase occurs at about the same time as the acceleration of the rotor 45. A typical pressure increase is from 2.8 at (41 psia) at point 40 in Fig. 1 at idle speed to 25.8 at (380 psia) at lift speed. This pressure increase can cause an increase in the diameter of the mantle (which is 2 times the length of the radius 41A in Fig. 2) of 0.1 mm (0.004 inches). The increase in mantle diameter is approximately represented by the area 43 in Fig. 3.

The third factor is the thermal expansion of the turbine bead 36 in Fig. 2: the temperature increase of the gas stream 14 causes the bead 36 in Fig. 2 to obtain an increased length 51. A typical temperature increase of the gas stream 14 from base speed to lift speed 1 may be from about 700 ° C (1300 ° F) to 11 about 1370 ° C (2500 ° F). This temperature increase causes the length 51 of Fig. 1 of the turbine bead 36 to increase, more specifically by as much as about 0.6 mm (0.025 inches). This thermal expansion of the bead is approximately represented by the decrease in the space in the area 38 in Fig. 3. This increase in length further strives to reduce the space 33 in Fig. 2.

The fourth factor is the thermal expansion of the mantein, which is caused by the increased temperature of the gas stream 14 and which increases the diameter of the mantein. However, the increase in mantle diameter is much slower than the three dimensional changes resulting from the three factors discussed above, and is represented by the gradual increase in mantle diameter indicated by the area 44 in Fig. 3.

The fifth factor includes the thermal expansion of the turbine disk 45A of the turbine rotor 45, shown in Figs. 1 and 35. Although the disk 45A is not exposed to the hot burner gases 14 in Fig. 1, it is in the vicinity of hot air, however. drained from the engine compressor 9.

Compressor drain means are used for such tasks as cleaning the engine's internal area 54 from lubricating vapors and other gases. The compressor drain means is at a higher temperature than the ambient temperature, which causes the turbine rotor 45 in Fig. 2 to gradually assume a higher temperature than the ambient temperature and thus expand. The expansion is gradual because the compressor drain means are not as hot as the air flow 14 (the hottest available compressor drain means is about 59000) and because the thermal mass of the rotor delays the heating of the rotor. The thermal expansion of the rotor is represented by the area 55 in Fig. 3. Again: the clearance 33 in Fig. 2 is affected by the following factors in the following approximate order. Initially (1), the elastic expansion of the rotor occurs, followed by (2) the pressure expansion of the housing. Then (3) the thermal expansion of the blades occurs, followed by (4) the thermal expansion of the housing. Then the thermal expansion of the rotor occurs (5).

A particular example of these dimensional changes will now explain: with reference to Fig. 3. The engine acceleration starts at the time 0 seconds.

The clearance at start is indicated by point 66 and is approximately 0.2 mm (0.0048 inches). After about 10 seconds, a lift speed of 11,000 rpm has been reached, sauces are shown in block 68, and centrifugal expansion of the engine causes an expansion to approximately point 71, thereby reducing the clearance.

In circle 90, a minimum clearance appears, which then increases with time. Such a minimum is called a "clamping point" and sets a limit on the minimum clearance 33 in Fig. 2 that can be built into the engine. For example, if the engine were designed so that its initial clearance would be clearance 93 in Fig. 3, the rotor would follow the dashed line 94 upon acceleration, and the rotor would strike the housing at point 96, which cannot be allowed.

Gaps in conditions other than the clamp point are greater than required. To reduce this unnecessarily large clearance, active clearance control is used to control the diameter of the housing 39 by blowing cold air onto the housing. As shown in Fig. 1A, fan outlet air 97A is directed to the turbine housing, as indicated by arrows 97, and a valve 134 controls the amount of air blown onto the housing.

Objects of the invention.

An object of the invention is to provide an improved clearance control in a gas turbine engine.

Summary of the invention.

This object has been achieved in that the device according to the invention has obtained the features stated in claim 1.

According to the invention, the instantaneous value of the clearance between a 468 Û59 4 turbine housing and a turbine rotor is calculated based on temperature. Two temperatures are used.

First, a steady state temperature (hereinafter also referred to as SSTemp) is calculated for the rotor and the housing. SSTemp is a calculated future temperature, which is reached when the engine reaches a steady state of operation. Each SSTemp is calculated based on currently occurring engine operating conditions, such as selected temperatures, pressures and speeds. Changes that occur in SSTemp indicate the other temperatures, which are the instantaneous temperatures of the housing and rotor. These changes in SSTemp are caused by changes in the current operating condition, which may occur during engine acceleration and deceleration. The instantaneous temperatures indicate the diameters of the housing and the rotor and thus the instantaneous clearance between them.

In another embodiment of the invention, the calculated instantaneous clearance is used to control air, which is drained from the fan and directed towards the housing, in order to achieve the desired clearance.

Brief description of the drawings.

Figs. 1 and 1A show in schematic cross section a gas turbine aircraft engine of the large bypass type.

Fig. 2 schematically shows in greater detail the area 30 in Fig. 1.

Fig. ZA shows a turbine blade 36, which is cooled by internal air currents 185.

Fig. 3 shows a diagram of the clearance 33 in Fig. 2 as a function of time.

Fig. 3A shows a cross-sectional view in greater detail of the area 30 in Fig. 1.

Fig. 4 shows an overview of a part of the invention, which is used to control the clearance of the high-pressure turbine 15 in Fig. 1 (Figs. 5 - 19 explain details in Fig. 4).

Fig. 5 shows details of the block 107 in Fig. 4 regarding the calculation of the rotor displacement of the high-pressure turbine.

Fig. 6 shows details of the block 209 in Fig. 5 regarding the calculation of the thermal component of the rotor displacement of the high pressure turbine.

Fig. 7 shows details of block 218 in Fig. 6 regarding calculation of the rotor temperatures of the high pressure turbine while the rotor is running.

Fig. 8 shows details of the block 211 in Fig. 6 regarding calculation of the thermal component of the rotor deflection of the high pressure turbine.

Fig. 9 shows details of the block 222 in Fig. 8, regarding the calculation of the rotor temperature of the high-pressure turbine, when the engine is not running.

Fig. 10 shows details of the block 126 in Fig. 4 regarding the calculation of the casing displacement of the high-pressure turbine. I p. 468 059 Fig. 11 shows an overview of calculations of the high-pressure turbine housing displacement.

Fig. 12 shows details of block 362A in Fig. 11 regarding calculation of the high pressure turbine housing temperature.

Fig. 13 shows details of the block 362 in Fig. 11 regarding the calculation of the casing displacement of the high pressure turbine.

Fig. 14 shows details of the block 138 in Fig. 4 regarding calculation of the amount of cooling air delivered to the high pressure turbine housing 39 in Fig. 1.

Fig. 15 shows details of the temperature delay network 266 in Figs. 7 and 12.

Fig. 16 shows details of the block 129 in Fig. 4 regarding the control system dynamics of the valve 134 in Fig. 1A.

Fig. 17 shows details of the block 630 in Fig. 16.

Fig. 18 shows details of block 101 in Fig. 4 regarding calculation of required turbine clearance of the high pressure turbine.

Fig. 19 provides a list of constants used to calculate Figs. 4 - 18.

Fig. 20 shows an overview of a part of the invention for controlling the clearance of the low-pressure turbine 18 in Fig. 1. (Figs. 21-34 explain details in Fig. 20.) Fig. 21 shows details of the block 756 in Fig. 20 regarding calculation of the rotor displacement of the low pressure turbine.

Fig. 22 shows details of the block 775 in Fig. 21 regarding calculation of the thermal component of the displacement of the low pressure turbine 14.

Fig. 23 shows details of the block 819 in Fig. 22 regarding setting time constants for the rotor of the low pressure turbine, based on operating conditions of the engine.

Fig. 24 shows details of the block 820 in Fig. 22 regarding the calculation of the rotor temperatures of the low pressure turbine while the engine is running.

Fig. 25 shows details of the block 830 in Fig. 22 regarding the calculation of the thermal component of the rotor deflection of the low pressure turbine.

Fig. 26 shows an overview of the calculation of the hollow displacement of the low-pressure turbine.

Fig. 27 shows details of block 939 in Fig. 26 regarding calculation of the thermal envelope displacement of the low pressure turbine.

Fig. 28 shows details of block 970 in Fig. 27 regarding modification of the low-pressure turbine housing time constants based on the engine operating point. Fig. 29 shows details of the block 973 in Fig. 27 regarding the calculation of the casing temperature of the low pressure turbine.

Fig. 30 shows details of block 976 in Fig. 27 regarding calculation of the housing displacement of the low pressure turbine.

Fig. 31 shows details of block 766 in Fig. 20 regarding calculation of the amount of cooling air flow delivered to the low pressure turbine housing 744 in Fig. 1A.

Fig. 32 shows details of the temperature lag network 825 in Figs. 22 and 29.

Fig. 33 shows details of block 753 in Fig. 20, regarding calculation of required turbine clearance of the low pressure turbine.

Fig. 34 gives a list of constants used in the calculations in Fig. Zo-sa. Fig. 35 shows a cross-sectional view of a turbine disc.

Fig. 36 shows a temperature-time diagram S of a second order heat transfer model.

Fig. 37 shows a linear setting of a coefficient of thermal expansion based on the temperature.

Fig. 38 shows the significance of a cold-play constant, such as KHPTCI in Fig. 4.

Detailed description of the invention.

(A) System overview.

Fig. 4 shows an overview of an embodiment of the invention. Block 101 calculates a desired clearance 33, shown in Figs. 2 and 3A, to be achieved during (a) the present core speed, given on line 104 in Fig. 4, and (b1 - the present rotor displacement, given by block 107. ( Displacement refers to deviation of the rotor radius 48A in Fig. 2 from the radius present when the rotor is cold The term "rotor" refers to the component which includes both the rotor disk 45A in Fig. 1 and the turbine blades 36 in Figs. 1 and 2. : the disc and retorf are treated as separate components, although the latter includes the former).

The rotor displacement in block 107 is based on measurements of the following rotor operating parameters: (a) actual (uncorrected) core speed; (b) total temperature at the high pressure turbine inlet, calculated at point 109 in Fig. 1 based on measurement at point 761 in Fig. 1A; (cl) the ethical pressure of the compressor emission measured at point 112; and (d) the total temperature of the compressor emission, similarly at point 112.

The displacement is treated as an overlay of three individual displacement components. The first component is the centrifugal displacement produced by the rotor speed and temperature, which later affects the modulus of elasticity of the rotor material, and thus the magnitude of the rotor expansion due to the centrifugal force.

The second component is the thermal displacement of the turbine blades 36 in Fig. 2, which is caused by changes in the blade temperature. The blade temperature is affected by the temperature of the air flowing around the blades (e.g., the air stream 14 in Figs. 2 and 2A), and the temperature of the cooling air flow 185 in Fig. 2A, which passes through the interior of the blades.

The third component is the thermal displacement of the rotor disk 45A in Fig. 1. The magnitude of this displacement is determined by the temperature of the disk 45A, which is affected by both the temperature and the heat flow conditions of the medium surrounding the disk.

This rotor displacement, which is determined by the block 107, is added to the desired clearance in a summer 120, in which also a constant K1 is subtracted (K1 is equal to the constant KHPTC1 in Fig. 19). K1 indicates the deviation of (a) the actual clearance in the turbine, when the turbine is at room temperature, ie. at a cold temperature, from (b) the desired clearance indicated by block 101 in Fig. 4 when the rotor is cold. Kl is thus the pre-existing clearance in the turbine and affects the required casing displacement on line 121, because K1 affects the magnitude of the additional displacement required to make the clearance correct.

Block 126 in Fig. 4 calculates the actual casing displacement, which is the displacement of the casing diameter 42 in Fig. 1 from the diameter present when the casing is cold. As with the rotor displacement, the housing displacement is composed of more than one component, and these components include a thermal expansion component and a pressure expansion component. The heating component is based on both (a) casing temperature and (b) the change in the coefficient of thermal expansion in the casing that occurs when the temperature changes. The pressure component is the expansion due to pressure changes in the turbine casing.

The required envelope offset generated by the summator 120 on line 121 is reduced in the summator 123 by the actual envelope offset, sm calculated in block 126, thereby obtaining an envelope error signal on line 124. The error signal indicates the difference between the actual envelope offset and the required envelope offset. For example, if a rotor growth occurs which increases the signal on line 207, the required envelope offset on line 121 increases and the envelope error on line 124 also increases.

A valve control block 129 receives the housing error signal and generates a signal on line 131 which drives the valve 134 in Fig. 1A to the proper position for the purpose of providing the proper amount of fan drain to the housing 39 for the purpose of achieving the displacement required by the signal on line 212 in Fig. Block 466 provides another signal on line 137 which informs valve control block 129 of the direction and speed at which the housing is expanding or shrinking. In response, block 129 modulates the required valve position on line 131 in order to avoid abrupt movements of valve 134.

For example, if the housing expands rapidly to the required diameter, it is advisable to gradually set the valve position for the purpose of slowing down the expansion of the housing as it approaches the intended diameter, rather than allowing the housing to approach the required diameter rapidly and then abruptly activating cooling air immediately. before the casing reaches the required diameter. Such transverse actuation requires that the valve be opened abruptly, which is not desirable. The signal on line 137 indicates the change in the rate of expansion of the housing and block 129 causes gradual opening and closing of valve 134. Block 129 performs other functions, which will be described later.

The foregoing discussion has dealt with the operation of the invention during the stationary state of the engine. In addition, the invention calculates rotor and housing displacements under non-stationary conditions, ie. during transients, such as accelerations and decelerations. This is done by monitoring how the calculated stationary temperatures of the rotor and the casing behave. Based on both the direction and speed of the change of these temperatures, the invention estimates the present and respective temperatures. (In general, it is not possible to transiently calculate these temperatures based directly on the operating parameters given on the left in Fig. 4, because a finite time is required for the components to set their temperatures in response).

This discussion will now touch in more detail on the calculations indicated in the overview according to Fig. 4. The details of the calculation of the rotor displacement in block 107 will be touched on first.

(B) Rotor displacement of the high pressure turbine, overview (fig. 5).

Fig. 5 shows an overview of the calculation of the rotor displacement, the details of which are given in Figs. 6 - 9. In general, as mentioned above, the overlay is of three individual displacements, each caused by different factors. One factor is the centrifugal force, which changes the diameter of the rotor itself. Another factor is the temperature, which causes the diameter of the rotor to increase as its temperature increases. A third factor is the change in turbine blade length 51 in Fig. 2, which occurs in response to temperature changes.

More specifically, in Fig. 5, the core speed is input to the multiplier 170, which multiplies the core speed by itself so that the square of the core speed is given to the multiplier 173. One reason for this squaring is that the centrifugal force is a function of the core speed raised to 2 (closer determined 9,468 Û59, the centrifugal acceleration is equal to wzr, where w is the speed in radians per second and r is the radius). The square of the core speed therefore allows one to calculate, using the block 176, the magnitude of the rotor expansion caused by the centrifugal force, and this expansion is called elastic displacement.

However, knowledge of only the core speed alone does not allow one to correctly calculate elastic displacement, due to the modulus of elasticity changing with temperature changes. Block 176 therefore receives the compressor's emission temperature, from which the temperature of the rotor disk and thus the actual modulus of elasticity can be determined. (As discussed in the background of the invention, compressor draining means are used to clean the area containing the disc 45A, so that the disc temperature can be obtained from the draining temperature). As a result, the output signal of the multiplier 173, the elastic expansion of the rotor is calculated by means of rotor temperature and centrifugal force, and is fed to the summer 179. This elastic expansion or centrifugal displacement is the first of the three superimposed expansion components.

The second component of rotor expansion is the thermal expansion of the rotor blades, which occurs in response to temperature changes in the blades. The temperature of the blades is affected by the temperatures of two air flows, namely the temperature of the compressor outlet and the turbine inlet temperature, as indicated by lines 181 and 183. One reason for this double dependence is that, as shown in Fig. 2A, the blades are surrounded by an air flow 14. is at or near the turbine inlet temperature. Furthermore, the blades are cooled by air currents 185, which are supplied from a compressor outlet. In general, the resulting temperature of the blades will be between the temperatures of these two air streams. The constants in blocks 177 and 189 in Fig. 5, the values of which are given in Fig. 19, are weighting factors which are to cause an interpolation between these two temperatures. Using these two constants, for example, a turbine inlet temperature of about 131506 (24D0 ° F) and a compressor outlet temperature of about 482 ° C (900 ° F) result in a blade temperature of approximately 740 ° C (1365 ° F), calculated as follows: I and since the blade temperature is known, the heat displacement of the blade is calculated in block 192. The thermal displacement of the blade is added in the summer 179 to the elastic expansion of the blade and the output signal on line 194 is called rapid rotor displacement RRD. The output signal is termed "fast" because it occurs almost instantaneously: The centrifugal displacement generated by the summer 173 is immediate and the thermal expansion of the blade provided by block 192 is practically immediate, mainly due to the large surface area of the blade being exposed. 468 059 for the two air streams 14 and 185 in Fig. 2A. The RRD signal on line 194 is supplied to the summer 196 and also to calculation blocks in other figures, as will be described in more detail below.

The third component of the total rotor expansion is the thermal displacement of the disk 45A in Fig. 1. Details of the calculation of this displacement are given in section (B) (1) below. For Fig. 5, however, it is sufficient to note that the heat shift of the disk 45A in Fig. (I.e., the diameter change) present on line 199 is added to the RRD signal in the summer 202.

The output 207 of the summer 202, also shown in Fig. 4, thus gives the sum of the three components, and the total displacement of the tips 205 of the turbine blades of Fig. 1A, which will be in a stationary state under the conditions indicated by the parameters of rows 104 and 181-183 in Fig. 4.

This calculation of the rotor displacement, which has just been discussed, has been based on the state of steady state of the motor. When motor transients occur, the displacement will be calculated by the block 107 in a manner which takes into account the deviation from the stationary state, as will be described in more detail later. The details of the calculation in block 209 in Fig. 5, relating to the heat displacement of the rotor, will now be discussed with reference to Fig. 6.

(B) (1) Heat displacement of the high pressure turbine disk (Fig. 6).

In Fig. 6, block 211 calculates the displacement of the disk based on the temperature of the disk applied to line 214. The temperature is calculated in two different ways, depending on whether the motor is running or not. When the engine is running, the disk is located in a hot environment and the calculation used is in block 218. On the other hand, the engine is not running, the disk is not in such a hot environment, but loses heat, and the calculation used is that of block 222. "Disc" refers to component 45A of Fig. 1 and does not include the turbine blades 36 of Figs. 1 and 2.

Whether or not the engine is running is obtained from an engine status indicator on line 210 and supplied by an engine fuel control known in the art intended herein. The status indicator controls a switch 212, which determines the type of calculation fed to the disk offset block 211. (Both calculations occur during each calculation iteration, but only the one selected by switch 212 is sent to block 211).

The switch 212 is in the false state in Fig. 6, which means that the motor is running, so the temperature signal reaching the line 214 is that generated by the block 218, which will now be explained. 11 468 059 (B) (1) (i) Temperature of the high-pressure turbine disc, engine running (Fig. 7).

Block 218 in Fig. 6 is shown in more detail in Fig. 7. In Fig. 7, the disk temperature that would be obtained at steady state, if the core speed and the compressor discharge temperature continue to have their present values, is calculated from block 235 and the multiplier 233. The core speed is supplied on line 263 and the total temperature of the compressor emission is supplied on line 238. (The temperature is converted to degrees Kelvin in a summer 230). Although a single line 240 is shown than the calculated data, in reality two temperature signals, one for each of the two parts of the disc, namely a hole and a life. Only one line 240 is shown for simplicity. The reason why the disc is divided into a hole and a life will now be explained. Fig. 35 shows a turbine rotor 45. One area is the web 45B and the other area is the hole 450. If the diameter of the disc 45 (excluding the blades 36) is 100 units, the hole, as shown in Fig., Is considered to be between 0 and 40 units , while life ranges from 40 to 100 units.

The hole and the life have different geometries, so that despite the fact that they are constructed of the same material, we will at a given ambient temperature the thermal displacement of the hole radius differ from the thermal displacement of the life radius.

A simpler example will illustrate the basic principles.

Consider a cube and a long rod, the length of which is 10 times longer on one side of the cube. Both are constructed of the same material. If both are raised to the same temperature, the elongation of the long rod will be greater than the elongation | at one side of the tube. Similarly, the thermal displacement of the hole and the life will be different, and the life and the hole will be treated differently in the calculations according to Fig. 7.

The calculated steady state temperatures of the hole and web are fed to a delay network 266 on line 270, after conversion back to ° C in the summator 241. On steady state operation is maintained, the delay network 266 at output 268 provides the temperature on line 270 without change.

However, during non-steady state operation (ie, during transients), the delay network 266 serves to estimate the hole and life temperatures. While the operation of the delay network is described in detail later, the operation of the multipliers 254 and 256, which provide two time constants to the delay network, will now be discussed.

The time constants in blocks 250 and 252 are specific to the hole and the life and are used by the delay network to estimate how quickly the hole and the life each receive or lose heat. Furthermore, the time constants are not in reality "constant", but they change when the operating point of the motor changes, and the changes of the time constants are made in the multipliers 254 and 256.

The time constants are used in a second order mathematical model, which describes the heat transfer behavior of the disk (as well as this behavior of other components, as will be described later) under motor transients.

By "second order" is meant that a graphical curve of the thermal behavior of the disk can be seen as the combination S of two separate curves P1 and P2, as shown in Fig. 36. Each separate curve has its own time constant, which is the resp. the constant in block 250 or 252. The changes in engine operating point that affect the time constants are obtained from an engine power parameter on line 246, which is a term including actual core speed, as indicated, multiplied by the ratio of compressor emission static pressure divided by total compressor emission total temperature.

The power parameter is thus of the form (N) (P / T), where N is the core speed, P is the compressor emission pressure and T is the compressor emission temperature. The parameter generally indicates the current output power of the engine.

A simplified explanation of the reason why the time constants of blocks 254 and 256 depend on the power parameter on line 246 is as follows. Core speed indicates the rotational speed of the disc 45A in Fig. 1, and thus indicates how much the disc is scrubbed by the ambient air. More scrubbing facilitates greater heat transfer, such as waving a hot spoon in the air facilitating the spoon to cool. Consequently, it is clear that the time constants should depend on the core speed, which is part of the power parameter.

The time constants also depend on the pressure and temperature of the medium surrounding the disk, because a hot, dense medium facilitates heating of the disk better than a hot, dense medium, which in turn heats the disk faster than a hot, less dense medium. medium. It is thus clear that the time constants should also depend on the emission temperature and pressure of the compressor, which affects the pressure and temperature of the cavity containing the cavity.

Therefore, in Fig. 7, the disk temperatures in the steady state, (i.e., those of holes and webs) are fed to the delay networks 266 on line 270. The delay network delivers, as will be explained later, these identical temperatures to its output 268 for steady state operation. continues. In such a case, the time constants generated by the multipliers 254, 256 are not used. However, if a transient occurs, the time constants are used to modify the steady state temperatures, as will be described later.

Three important features relating to Fig. 7 are as follows. First, the disc has been divided into two components, namely a hole and a life. There are 13 468 059 two time constants (one in block 250 and one in block 252) for each component, which gives a total of four time constants for the disk.

Second, as indicated by the designation 273, each line supplying the delay network 266 represents two pieces of data, one for the life and one for the hole.

Third, the temperature signal on line 238 provides an implicit height correction: the ambient temperature changes as the altitude changes, causing the compressor discharge temperature to change, thus affecting the disk temperature through the multiplier 233.

The steady state hole and life temperatures on line 240 are modified during motor transients (ie, non-stationary) by the delay network 266, which is explained below in connection with Fig. 15. However, prior to the discussion of transient temperatures, Fig. 8 will first be modified. is discussed, which indicates the calculation of disk displacement based on both the hub and the bit temperatures on line 268 in Fig. 7.

It can be pointed out that the disc displacement calculation in Fig. 8 is used not only when the engine is running, both during steady state and during transients, but also when the engine is not running, although the situation with transients and when the engine is not yet running has been discussed.

(B) (2) Displacement of the high pressure turbine disc (Fig. 8).

The temperatures generated by the delay network 266 in Fig. 7 (or line 220 in Fig. 6, as discussed later) are fed to line 214 in Fig. 6, which leads to the disk displacement block 211, which will now be explained with reference to Fig. 8.

Fig. 8 is symmetrical about the line 281 and thus the explanation given for hole deflection calculations which take place above the line is the same for those which relate to life calculations which take place below the line.

Simplified, Fig. 8 finds the increase in the length of an object (i.e., life or hole) by multiplying the length (in block 308), which is present at a reference temperature (in block 309) by both (a) the deviation from the reference temperature (in block 309). line 299) and with (b) the coefficient of thermal expansion of the object.

The length increase is thus equal to (T1-T2) x (coefficient of expansion) x (original length), where T1 is the actual temperature and T2 is the reference temperature.

This calculation is explained in greater detail as follows. The hole temperature, which is that on line 268 in Fig. 7, and which, during steady state operation, is the same as that on line 270, is fed to the multiplier 280 in Fig. 8. The multiplier 280, together with the adjacent summer 283 , sets a coefficient of thermal expansion (TEC), based on temperature changes of the material for which the coefficient has been derived, and can be explained with reference to Fig. 37. Fig. 37 shows a straight line 281A, which is described by an equation of the shape Y = Mx + B. The symbol M represents the slope of the line and B is the point of intersection with the Y axis, which is indicated by the point 2818. In Fig. 8, M is the constant included in block 288 and B is the constant included in block 293. Thus, if X (i.e., the temperature) is the input to the multiplier 280 as indicated, on line 286, the output of the summer 283 represents MX + B. This output represents the coefficient of thermal expansion (TEC) of the hole material, but adjusted for the hole temperature. The adjustment is linear, based on the straight line 281A in Fig. 37, but uses the constants of blocks 288 and 293 as M and B.

After adjustment, the coefficient of thermal expansion in the multiplier 301 in Fig. 8 is multiplied by the deviation (DELTA-T) of the actual hole temperature, on line 214, from the room temperature (or the second reference temperature), on line 297. The deviation is applied to multiplier 301 on line 299 The multiplier 301 further multiplies the TEC and DELTA-T by a reference radius of the disk given on line 304. The reference radius represents the radius of a reference point 318 on the disk, as shown in Fig. 35.

Fig. 8 calculates the displacement 319 in Fig. 35 (shown greatly exaggerated) of the reference point 318, which is caused by temperature changes, and gives the displacement on the line 306.

An identical calculation is made for the life and is made below the line 281. A similar reference point 318B in Fig. 35 for the life is given by the block 312 in Fig. 8, and the line 310 thus gives a signal indicating displacement 3180 of the life reference point.

The output of the summer 313 in Fig. 8 indicates the sum of hole and life displacements and thus indicates the heat displacement of the disc 45A.

The previous discussion has considered the calculation of disk displacements for a running motor. However, if the stator signal on line 210 in Fig. 6 indicates that the motor is not running, the calculation used is that of block 222, which is given to line 214 by switch 212. Block 222 calculates disk temperatures based on both the time during which the motor has been switched off, approx. the disc temperature at the time of switching off. This calculation will now be considered.

(B) (1) (ii) High pressure turbine disc temperature, engine not running (Figs. 6 and 9).

Block 222 in Fig. 6 receives four inputs, one of which is a motor designation on line 244. This designation is in fact a serial number which identifies the motor. This serial number is given by the electronic fuel control (not shown) of the engine, in a manner known in the art. Block 222 thus informs about the identity of the engine with which block 222 w a 468 059 previously associated. One reason for achieving this designation number is the following.

It is possible that the game room control hardware incorporating the invention described herein may have been replaced with new control hardware. In such a case, the new control device, using the block 222, will detect a change in the designation number on the line 224. (According to the invention, a constant request is made as to whether the designation number of the motor remains the same). Once the new motor designation has been established, indicated by the symbol T in Fig. 9, the life and hole temperatures on line 220 in Fig. 6 are set to an assumed value, namely the constant KHPTCI9 in Fig. 19, which is 150 ° C.

One reason for this setting to an assumed value is that the new clearance control hardware does not know the time elapsed since the engine was turned off nor the disk temperature at shutdown, and therefore cannot estimate the disk temperature based on the shutdown temperature and elapsed time.

Instead, an assumed value of 150 ° C is selected. This value is considered acceptable because it is close to the temperature of a disc in operation, so that problems similar to those in the event of a hot rotor failure will not occur. The clearance control device thus assumes that there is a hot disk, when the controlling hardware changes, independent of the actual temperature of the disk, and independent of the time during which the disk has cooled down.

On the other hand, the designation parameter just discussed indicates that no change of control hardware has taken place, the disk temperature is calculated as expressed in Fig. 9: Temp = (TOLD - TREF) [exp (-TIMEOFF / TIMECON STÅJ 4-TREF where Temp refers to the disk temperature, TOLD refers to the disk temperature at shutdown, TREF refers to a reference temperature that is approximately equal to the temperature (TOLD-TREF is thus equal to the temperature increase of the disk), EXP refers to the base of the N-logarithm, namely e, TIMEOFF is the time, during which the motor has been switched off, and TIMECONST refers to the respective time constant in Fig. 19 for the hole (KHPTDBORETSD) or the life (KHPTDWEBTSD).

The previous calculation is done twice: once for life and once for the hole. Both calculations are, as can be seen from the expression types of exponentially decreasing functions. As an example, a calculation will now be given here. 468 059 16 As Fig. 19 indicates, the time constant (KHPTDBORETSD) for the hole is 438 min, while for life (KHPTDEWEBTSD) it is 375 minutes. If the difference TOLD minus TREF is 100000, while TREF is 30 ° C, then the estimated temperature for life after 750 min. (ie after the course of two time constants) approximately 1650 calculated as follows: 165 = 1000exp (-750/375) + The temperatures calculated by block 222 in Fig. 6, as just described, for both the hole and the life, are fed to block 211, which calculates the actual disk displacement, as described above under the heading "(B) (1) Heat Shift Turbine Pulley (Fig. 6)". This thermal displacement of the disk is one of the three components of rotor growth, and is added on line 199 in Fig. 5 to the RRD of the summer 202, as indicated above.

The foregoing discussion has explained the calculation of the rotor displacement made by block 107 in Fig. 4. This displacement is fed to the summer 120, which also receives a desired clearance from block 101 for the purpose of generating a desired casing displacement. The calculation of the desired clearance will now be discussed with reference to Fig. 18.

(C) Calculation of desired clearance (Fig. 18).

In Fig. 18, block 440 generates a desired clearance 33 in the stationary state in Fig. 2 in response to the core speed. An example will illustrate how the rest of Fig. 18 works.

Assume that the desired clearance on line 443 is 0.25 mm (0.010 inches). In the steady state, rapid rotor displacement (RRD, which is the sum of the heat displacement of the blades and the centrifugal displacement of the rotor on line 194 in Fig. 5, as discussed above) obtains a certain finite value which is stable, such as 0.38 mm (0.015 inches). The Z-block 447 in Fig. 18 supplies the last preceding value of RRD to the summer 448 and, as long as the RRD remains constant, the value of the summer 448 on line 450 is zero. (0.58 mm is subtracted from 0.38 no.).

A MAX selector 456 selects the larger of the signal on line 450 (now zero) or the constant in block 453. As shown in Fig. 19, the constant has a value of about 0.01 mm (0.0004 inches), so that at this time block 456 selects 0.01 mr and adds this value to the summator 460.

The summer 460 also receives the last value of the line 463 from the Z-block 466. The MAX selector block 468 selects the larger of (al the value from the summer 460 or (b) the signal on the line 443. In this example, the signal is on the line 463 0.25 mm so that the output value from the summer 460 is (0.25 - 0.01 mm) or 0.024 mm, so the block 468 selects the signal on line 443 and supplies it to line 463. Therefore, the output value on line 463 is equal to that desired clearance in the steady state from block 740 as long as the steady state is present.

When a transient occurs, the same output signal may or may not be obtained, as will now be explained. Assume that the core speed increases. RRD is jumping now. Assuming that the RRD jumps to 0.5 mm, the signal on line 450 in Fig. 18 now jumps to 0.125 mm (0.5 - 0.38). The max selector block 456 selects this value instead of the 0.01 mm option, and adds 0.125 mm to the summer 460, which subtracts this value from the previous stationary value on line 463.

One way to visualize the significance of this subtraction is shown in Fig. 38. A blade 36 and housing 39 are shown in their stationary states. Since there is a steady state, the clearance 486 will be equal to the required clearance on line 463 in Fig. 18. As the core selection jumps, RRD increases as indicated by distance 489 in Fig. 38, which corresponds to the value on line 450 in Fig. 18. The summer 460 takes the difference between the play space in the stationary state (the distance 486 in Fig. 38), which is generated by the Z-block 466 and the increase of the RRD (the distance 489 in Fig. 38). This difference 492 is the remaining clearance in the turbine after the jump in the RRD.

The max selector 468 selects the larger of this remaining clearance 492 in Fig. 38 or the registered clearance for the new higher core speed (from block 440 in Fig. 18). (In general, the desired clearance of block 440 decreases as the core speed increases). As a result, the required clearance on line 463 will be equal to or less than the previous clearance in the stationary state. Furthermore, the value of line 463 will not decrease faster than RRD increases, provided that the increase of RRD is less than the limiting value in (block 453. The effect of this new requested clearance will now be explained with reference to Fig. 4.

The reader is reminded that the clearance is only regulated by cooling, and thus shrinking, of the housing 39. Removal of the cooling air, such as by closing the valve 185 in Fig. 1A, allows expansion of the housing 39, when the turbine gases 14 heat it. Reducing the desired clearance value, generated by block 101 in Fig. 4, causes the required casing offset (on line 121) to decrease, causing the casing error to decrease, which in turn causes the cooling valve to restrict flow or shut it off completely. The effect is that the housing is allowed to expand during accelerations to make room for the growing turbine. This effect is significant during the growth of the hot rotor, as discussed above under the heading "Background of the Invention".

After the acceleration is completed, however, the RRD in Fig. 18 assumes a steady state value, which drives the output of the summer 440 to zero. 468 059 18 The MAX selector 456 thus selects the constant in block 453 and supplies it to the summer 460. The desired clearance on line 443 reaches its final, lower value due to the acceleration having stopped, but the core speed is now higher.

(The reader is reminded that the desired clearance decreases as the core speed increases).

Thus, since the previous value of line 463 is less than the value of line 443 (because the MAX selector block 468 previously selected the larger of the output value from the summator 460 or the signal on line 443, and the signal on line 443 has decreased), the effect becomes of the summer 460 and the MAX selector block 468 to incrementally reduce the demand clearance, on line 463 in steps of 0.01 nm to the new, lower clearance, which is correct at the higher core speed.

The foregoing discussion has shown three main functions of the apparatus of Fig. 18. First, during steady state operation, the desired clearance of block 440 appears on output line 463. Second, during an acceleration, the required clearance is reduced so that the cooling valve in Fig. 1A limits or closes completely, and thus allows housings 39 to grow and make room for the growing rotor. Third, after completion of acceleration, the output signal on line 463 is gradually brought to the stationary state value on line 443, in steps of 0.01 mm, which step is the constant in block 453.

The requested clearance is supplied to the summer 120 in Fig. 4 together with the rotor displacement, as described above, to generate the desired housing displacement on line 121. The constant K1 is subtracted in the summer 120, as will now be explained.

Kl is a previously available clearance, which is built into the engine during manufacture. In general, Kl will vary between 1.52 and 2.03 mm. If the components of Fig. 38 are cold, dimension 486 would represent Kl.

As a blade grows to the dashed position 368, the desired clearance from the block 101, when added to the summer 120, indicates that the housing 39 should be at point 480. However, the cold clearance 486 (ie, K1) provides a previously available clearance. and is subtracted from point 480 in determining the required casing displacement. The subtraction indicates that the housing 39 only needs to move the distance 482 to achieve the desired clearance.

The output of the summer 120 in Fig. 4 indicates the required casing displacement. The actual envelope offset is subtracted from it in the summator 123 for the purpose of giving the envelope error. The calculations of the displacement of the casing will now be discussed. f) H J 19 468 059 (D) The casing temperature of the high-pressure turbine (Fig. 10) Briefly, the casing displacement is divided into three components, the upper layers of which give the total casing displacement. The three components are, first, heat displacement, on line 323 in Fig. 10; second, pressure shift, on line 328; and, third, heat dissipation of the housing supports, on line 325. (The housing support displacement is subtracted in the summer 326 because expansion of the supports, such as the supports 430 in Fig. 3A, serves to reduce the housing diameter, while expansion of the housing itself serves to increase the casing diameter).

The calculations of the heat displacement will now be treated in detail.

The block 320 in Fig. 10 receives four inputs 329 and calculates from them the deviation in the casing diameter from its cold state. This calculation is described in more detail in Figs. 11-13.

As indicated in Fig. 11, the envelope temperature is first calculated and then the heat displacement is calculated based on this temperature. The temperature calculation is given in further detail in Fig. 12. As with the rotor, Fig. 12 shows two time constants in blocks 398 and 401, due to the fact that the heat transfer model of the casing is also of the second order type. Furthermore, as with the rotor, each time constant is in fact not constant, but is modified by the block 393 according to the core air flow, which is the amount of air moving through the housing and indicated by the arrow 14 in Fig. 1A.

One reason for modifying the time constants according to the core flow (or "flow") is analogous to that for modifying the time constants in Fig. 7 for the rotor. The rate of heat transfer from the housing 39 in Fig. 1 is related to the temperature and density of the medium in contact with the housing, and this medium is the air flow 14. Although the core air flow is a single parameter, this single parameter contains information on the heat transfer properties of the air stream 14. approximately the same as the power parameter on line 246 in Fig. 7 contains information about the heat transfer properties of the disc contacting medium.

For large core flows, for example, the temperature of the air stream 14 is generally high, the pressure (ie the density) is high, and the speed is high. With small air flows, the temperature is lower, the pressure is lower and the speed is lower. Knowledge of the core flow through block 393 therefore allows calculation of the rate of heat supply to and from the housing, which affects the time constants of the housing.

The steady state temperature of the housing is given on line 405 in Fig. 12 and is calculated on the basis of parameters 407, which include the total temperature of the compressor emission and the total temperature of the fan emission. In addition, a signal on line 421A indicates the relative mass flows of the two air streams having these two temperatures. Compressor exhaust air is used to cool the housing 39 and jacket supports 330, and flows roughly as indicated by arrows 431. The fan cooling air flow is indicated by arrows 97 and supplied by a chamber 98, which is shown in rough lines.

The block 418 in Fig. 12 contains a factor known from the construction of the compressor drain, which when supplied to the movement condition provided by the line block 416 gives the scale factor which defines the action of the two air streams 431 and 97 on the housing in Fig. 3.

From another point of view, the apparatus leading to line 405 in Fig. 12 provides the temperature of the fan drain air flow 97 in Fig. 3A, together with the temperature of the compressor drain air flow 431. Block 418 further contains information known from the housing 39 construction regarding the heat transfer properties. of the casing and associated structures. Knowledge of the previous information allows calculation of the temperature of the casing.

More generally, line 405 represents an interpolation between the two air flows at different temperatures. First, the temperature difference is obtained from the summer 415, the difference is weighted by the multiplier 421, and the weighted difference is subtracted from the warmer temperature in the summer 424.

The weighting of the multiplier 421 is based on the ratio of mass flows given in the divider block 416 and also on the flange efficiency given in the block 418. The latter is known in the heat transfer theory and is an indication of the thermal insulation value of the components which are located between the heating and cooling air streams. The components of Fig. 3A include the housing 39, flanges 431A, as well as the housing supports 430.

The previous discussion has dealt with the calculation of the temperature of the housing in the stationary state. This temperature, like the rotor temperature in the steady state in Fig. 7, is supplied to the delay network 266 in Fig. 12, together with the correct time constants for the casing, and the output on line 427 indicates the casing temperature. In the steady state, the output is equal to the temperature in the steady state on line 405. During transients, the output is modified by the delay network and the time constants. The use of the casing temperature to calculate the casing displacement will now be discussed.

(E) Shaft displacement of the high pressure turbine (Figs. 11 and 13).

Fig. 11 shows that the casing temperature on line 427 is fed to block 362, which calculates the casing displacement. The calculation is shown in detail in Fig. 13.

As in Fig. 8, on line 502 in Fig. 13, the envelope displacement is calculated based on a dimension (in block 483) which occurs at room temperature (in block 486) and the dimension is multiplied both by the deviation from room temperature according to H 468 059 ( on line 489) and with the coefficient of thermal expansion (on line 499).

As described above in connection with Fig. 37, blocks 493 and 496 in Fig. 13 together with the multiplier 498 and the summer 501 adjust the coefficient of thermal expansion based on the temperature of line 427. The adjusted coefficient is multiplied by the deviation from room temperature (or other reference temperature) in the multiplier 503, in which the temperature dimension of the housing (in block 483) is also multiplied. The product on line 502 is the thermal offset of the housing and is in the form of (coefficient of thermal expansion) x (temperature deviation) x (original size). The heat displacement of the casing is supplied to the summer 123 in Fig. 4, from which casing defects are obtained.

(F) Calculation of cooling air flow.

The calculation of the amount of cooling air stream fed to the divider 416 in Fig. 12 will now be discussed. This calculation takes place in block 138 of Fig. 4, which is shown in detail in Fig. 14. The output of the divider 520 is the pressure ratio between the fan outlet, at point 523 in Fig. 1A and the pressure under the hood, which represents the pressure near point 526, and is calculated based at atmospheric pressure.

This pressure ratio is that in the duct 527, which delivers the cooling air flow to the housing 39, when the valve 134 is fully open.

It is known how to calculate the air flow rate in a duct, when the pressure ratio (from the divider 520), the temperature (on line 529), and the duct geometry are known (geometry factors are found in block 531). Thus, the signal on line 533 indicates the maximum cooling flow that can be applied to the housing 39. However, the valve 134 in Fig. 1A restricts this flow, and the actual flow is obtained from the valve position, on the line 536 in Fig. 14, which is corrected in the block. 539 for nonlinearities between valve position and valve opening. The result, on line 416A in Figs. 4, 12 and 14, is the amount of cooling air reaching the housing 39.

This discussion will now deal with the temperature delay node 'Figs. 7 and 12, both of which are the same, and which set the calculated temperature in the steady state of the rotor and the housing for the purpose of providing estimated temperatures of the rotor and the housing for use under transients. .

(G) Temperature delay network (Fig. 15).

The foregoing discussion has dealt with the calculation of casing faults fed to the valve regulator 129 in Fig. 4 but under steady state conditions. An explanation will now be given of the effect of the invention under motor transients, i.e. during accelerations and decelerations, for the purpose of estimating the rotor and casing temperatures based on the behavior of the calculated temperatures in the steady state. This estimation takes place by means of the delay network 266 468 059 22 in Figs. 7 and 12. The delay network in Fig. 7 processes both signals for the life and the hole. The delay unit in Fig. 12 processes signals for the housing.

The situation in Fig. 12, for the housing, illustrates the function in all three situations and is generally illustrative. The time constants in blocks 398 and 401 are applied in Fig. 15 as shown. Two delay networks are shown in Fig. 15, and they are identical. The first is upstream of point 578, while the second is downstream of pump 579.

In the first network, the divider 580 divides the time constant on line 583 by 0.24. The ratio of line 586 is another time constant, but set to the fact that the iteration time for the computer program is 240 milliseconds. In other words, point 578, or any other selected point in the figures, is reached once every 240 milliseconds while the program is running. However, the time constant on line 583 is calculated in seconds and set by divider 580.

The steady state temperature from line 405 of Fig. 12 is applied to the summator 589, where the Z-block 592 subtracts the last value occurring at point 578, and thus gives the temperature change occurring after the last iteration of the summator at point 593. This temperature change is multiplied by the time constant on line 586, which is a number between 0 and 1, and the product, on line 595, is added in the summator 598, of the z-block 592, to the last value at the point 578.

This sequence of events adds a delay to the temperature in the stationary state on line 588, as the following example will illustrate.

Let us assume that the temperature in the steady state increases from 10 to 15 and then stabilizes at 20 arbitrary units. Let us also assume that the time constant on line 586 is 0.5, meaning that the natural time constant on line 583 is 2.08. When the temperature was stable at 10, the value at point 5930 was 0 because the signals on lines 588 and 590 were equal. However, when the temperature jumps to 15, the value at point 593 (the temperature difference) assumes a value 5 (15 - 10).

The multiplier 601 now generates a value 2.5, which is added in the summer 598 to a value 10 (from the z-block 592) to produce a signal with the value 12.5 at point 578. During the next iteration, the temperature jumps to a value And the summator 589 generates an outside value of 7.5 (i.e., 20 minus 12.5). The multiplier 601 takes 1/2 of this value and adds the result 3.75 to the summator 598, which adds this number to the number 12.5, which gives a value in point 578 of 16.25.

At the next iteration, after the temperature has stabilized at 20, the value is 3.75 at point 593 (ie 20 minus 16.25), of which 1/2 is added to the value 16.25 at point 578 of the multiplier 601 and the summator 598 , which gives [i 23 468 059 18.125. This process continues, in which the difference between the value at point 578 and the temperature at steady state (ie 20) is divided by 2 and added to the value at point 578. In other words, the sums 589 and 598, together with the multiplier 601 , half of the difference between points 578 and 588 and adds this half to point 578 at each iteration. In this example, the sequence of values in paragraphs 578 is 10, 12.5, 16.25 and 18.125.

This process forces the value at point 578 to follow the steady state temperature on line 588, but with a time delay: the first evaluation (at point 578) does not immediately assume the steady state temperature, but gradually approaches the steady state temperature in steps about 1/2 of the present difference. The actual time for the delay is determined by the time constant. If the time constant were 0.1 instead of 0.5 as assumed above, the successive values at point 578 would be 10, 10.5, 10.95 and 11.1 instead of the sequence calculated above. A smaller time constant thus causes a greater delay and causes the signal at point 578 to take longer to reach the final value in the steady state. The value from the first delay network, in point 578, will be called a first delay temperature, and will be fed to a lead network 618, which will now be explained.

The first delay temperature is multiplied in the multiplier 605 by a constant on the line 607 which is approximately - 0.94, as shown in Fig. 19. The constant is also subtracted from 1.0 in the summer 609 and the result, about 1.94, is multiplied in the multiplier 613 with the temperature in the steady state on line 611. The values from the multipliers 605 and 613 are added in the summator 614, which gives a signal on the line 615. This signal serves as a led signal, which notifies the second delay network of the behavior of the temperature in the steady state : the signal is equal to (1.94 x the steady state temperature) minus (0.94 x first delay temperature), and is thus dominated by the steady state temperature.

The lead signal on line 615 is applied to a second delay network, which begins at point 579. The second delay network has a smaller time constant on line 620 but otherwise functions as the first delay network. Therefore, the output value, which is the estimated temperature of a component (casing, hole, or life) below a transient, is exposed to two delay networks as well as to the hinge network in block 16. The entire network is a delay hinge-delay network.

The foregoing discussion of the high pressure turbine clearance regulation has shown how rotor and casing offsets are calculated for stationary 468 059 2, conditions based on core speeds, pressures and temperatures to which the rotor and casing are exposed. Furthermore, the discussion has shown that transient displacement of the rotor and the casing which occurs when the motor is subjected to accelerations or decelerations can be calculated based on the behavior with time of the calculated steady state temperatures of these components. These transient calculations take place in the delay network 266 in Figs. 7 and 12.

The time constants in the delay network are modified under transients in response to selected operating parameters, such as those that feed block 260 in Fig. 17 and feed block 393 in Fig. 12. This discussion will now address the operation of the valve regulator block 129 in Figs. 4 and 16.

(H) Valve regulator dynamics (Fig. 16).

The valve regulator block is shown in more detail in Fig. 16. Information regarding the probable reliability of selected sensors is fed to a parameter status block 630. The sensors in question are those which indicate the total air temperature of the air entering the engine, ambient air pressure. , compressor discharge temperature, and low pressure turbine inlet temperature. These sensor reliability data are provided by other devices, which are known per se. Data for each sensor is a digital signal representing a number. The value of the number indicates the expected degree of reliability of the data obtained from resp. sensor. In the technology referred to here, these data are called selection stator parameters, hereinafter referred to as SST parameters (SST).

The SST parameters are applied to a truth table shown in Fig. 17, which represents the mode of operation of block 630 in Fig. 16. In column 700 in Fig. 17, a request is made as to whether the SST of the low-pressure turbine inlet temperature sensor is equal to 4 or 7. If the SST is equal to 4 or 7, the answer is T (true), ie. true, and if this is not the case F (false), ie. false. In column 701, an inquiry is made with respect to the SST of the compressor emission temperature sensor.

If SST is equal to 4 or 7, the answer becomes T, if not the answer becomes F. On the answer is indefinite, ie. if the answer is neither T nor F (a "do the same" state), then 1 s gets an x.

Column 702 asks if the SST of the ambient pressure sensors exceeds 13, while the column 703 makes a similar request regarding the SST of the total air temperature sensor.

The individual values in each row 705-709 are subjected to a logical OR operation, which means that the query is made as to whether at least one true answer is present in the row, and the result is given in column 704. The true answer in circle 710 gives, for example, row 707 an OR value T (ie true) as indicated in column 704. In contrast, the absence of a true answer in line 709 gives this line an OR value F, false. The true value indicates that the sensor data is not considered sufficiently reliable, and as explained below, the control device sets the valve 134 in Fig. 1 to a "fail-safe" position.

Based on the slot 704, the bypass switch 633 in Fig. 16 is driven to the "true" position shown when the answer in slot 704 in Fig. 17 has a true value. In this situation, the control loop is shown by the broken line 636 in Fig. 16 and the requested valve position is obtained from the summer 639. A cooling valve position of 0% from block 642 is supplied to the summer 639, from which the previous value of the requested valve position is subtracted. is obtained by the x-block 645. The value of the resulting signal on line 650 is limited by max and min selectors 653 and 656, which limit the signal between the values +22,222 and -22,222, as shown in Fig. 19. The resulting limited signal is applied to the summer 660 of Fig. 16, to which is added the previous value of the valve signal obtained from the z-block 663. The summer 660 and the z-block 663 act as an integrator which integrates the signal generated by the max-selector 656. Consequently, the valve position is determined by the output value from the summer 639.

No cooling is applied to the housing and the housing assumes its maximum diameter, which is a "fail-safe" mode. If the switch 33 is in the "false" position, indicating that a sufficient number of sensors are assumed to operate reliably, the stator error signal on line 670 is processed as follows. The error signal is multiplied by a gain function in block 673. The gain function gives different effects on different values of the stator fault. A stator fault of 0.5 mm (20 miles) can, for example, cause the output signal from the gain block to be 50 units, while a fault of 0.025 mm (one mile) can cause a disproportionately small output signal, such as one unit. One result is that the larger error of 0.2 mm (20 miles) causes a larger reaction (50 units).

A minimum selector 674 then selects between the minimum of the signal from the block 676 and the output of the gain block 673, thereby limiting the output of the gain block to an upper highest value, namely that in block 676. The output of the minimum selector 674 is fed to a multiplier 679, where it is multiplied by a constant included in block 682, whereby the error signal is converted into the correct units necessary for valve adjustment.

The constant converts the stator fault units into valve position units (ie the position of a valve disc or orifice) because a given stator fault requires a given amount of cooling air, which is obtained by means of a valve with a given valve disc position.

The output signal from a filter included in the dashed block 684 is also fed to the multiplier 679. The filter serves to filter out high frequency noise 468 059 26 which could occur in the stator error signal. An example will illustrate the filter's 684 operation.

In the steady state, the signals on lines 670 and 685 will be the same. Thus, the output of the summator 688 will be zero and the multiplier 690 does nothing to change the signal on line 685. However, when a jump in the stato error occurs, the filter actually asks if the jump represents a real stator troubleshooting or a false noise signal.

Assume that the previous error signal was 0.25 mm (10 miles), and that the error signal now jumps to 0.5 mm (20 miles). The value from the summer 688 is now 0.25 mm (0.5 - 0.25). Block 693 and multiplier 690 multiply this output by a fraction, which is assumed to be 0.10, giving a signal 0.025 (0.25 x 0.10) on line 694, which is added to the previous error signal 0.25 m in the summer 696.

The result is a signal of 0.275 on line 685, in response to an error signal of 0.5 on line 670: the large error signal has been reduced. If the large error signal remains, the signal on line 685 will gradually approach the value of the error signal. If the large error signal disappears, which happens if the cause was false factors, the signal on line 685 will gradually assume the initial value 0.25 on line 670.

The block 684 thus acts as a filter because it prevents fast (ie high frequency) jumps in the stator fault from spreading past the multiplier 679. The loop indicated by the arrow 695 will now be touched.

The max and min selector blocks 712 and 713 each receive a marginal signal of a resp. lines 651 and 650. Each margin signal represents the difference between the last requested valve position, obtained from a respective z-block 645 or 646, and boundaries from blocks 642 and 643. One boundary, in block 643, represents a maximum allowable valve position, while the other the limit, in block 642, represents a minimum allowable valve position. The margins thus limit the signal on line 715 through the max and min selector blocks 712 and 713.

The margins limit the valve speed when the valve approaches either the maximum or minimum positions. For example, if the requested valve position were very close to the maximum position, the difference generated by the summer 639A would be very small, so that the valve position allowed by the min selector block 712 would have the same small difference.

Similarly, the max and min selector blocks 653 and 656 restrict the signal on line 715, but for a different reason. These latter blocks prevent the requested valve speed obtained from the control system on line 715 from exceeding the fastest movement speed that can be achieved with the valve: the control device is not allowed to demand a valve movement speed that the valve e can achieve.

The output signal from the maximum selector 656 is fed to the z-block 717 and to the summer 660. It should be noted that this output signal, although previously described as a valve disc position, in fact represents a speed ho the valve disc. The signal is applied to a servomotor known per se, and as long as the signal is on, the servomotor operates the valve disc. The speed depends on the signal size. The Z-block consequently produces a rate of change of speed, which is an acceleration. Therefore, the line carries a signal indicating valve disc or valve orifice acceleration.

This acceleration signal modifies the signal from the multiplier 679 as follows. A fractional value is passed on line 719, based on HPTCMOD, which is the signal generated by block 393 in Fig. 12. HPTCMOD is the signal that modifies the casing time constants, as discussed above under the heading "(D) High pressure turbine casing temperature (Fig. 10)". The fractional value on line 719 supplies a portion of the previous acceleration, obtained from the z-block 720, to the summer 721, where the difference between the two accelerations is obtained on the line 722. The difference is added to the previous value in the summer 723 and the result is subtracted in the summer 724.

One way of considering the modification just described is that calculation one in the dashed block 725 serves to adapt the requested acceleration, generated by the maximum selector block 656, to the acceleration to which the housing can be subjected, based on its present time constants. If too much acceleration is requested, the summer 723's output signal serves to reduce the requested acceleration, generated by the max selector 656, due to the subtraction occurring in the cm 725.

(I) Overview of the low pressure turbine system (Fig. 20).

This discussion will now relate to a control system used to control the clearance 740 in Fig. 1A between the low pressure turbine 18 and the low pressure turbine housing 744. A fan drain similar to that used for the high pressure turbine is used, as indicated in Fig. 1A.

Fig. 20 is an overview of the system, with similar contents as Fig. 4.

Block 753 in Fig. 20 calculates the desired size of clearance 240 in Fig. 1A, based on fan speed. Fan speed is used in Fig. 20, in contrast to the actual core speed used in Fig. 4, because the fan 21 in Fig. 1A is attached to the same shaft as the low pressure turbine 18, and the term "fan speed" is an accepted term in the present invention. the low pressure part technology, which includes the fan 21, the amplifier 6 and the low pressure turbine 1 468 bucket, 28 Block 756 calculates rotor displacement based on four input parameters: fan speed; the temperature of the cavity 757 in which the rotor disk 758 of Fig. 1A is located; total temperature of the low pressure turbine inlet; and the static temperature of the low-pressure turbine inlet. These four parameters are analogous to the four parameters used by block 107 in Fig. 4, for the high pressure rotor displacement: the fan speed is analogous to the core speed; the pressure of the low-pressure turbine inlet is analogous to the static pressure of the compressor outlet due to the fact that each exerts pressure on its respective turbine housing; the temperature of the low pressure turbine inlet is analogous to the temperature of the high pressure turbine inlet; and the cavity temperature is analogous to the compressor discharge temperature, because the latter is used to clean the high pressure turbine cavity, as described above. The output of block 756 in Fig. 20 indicates rotor displacement, which is added in the summator 764 to the desired clearance from block 753, from which the cold clearance in block 767 is subtracted. The output of summator 764 is the requested housing position.

The deviation of the casing from this requested position is determined in the summer 770, which calculates the casing error. The input signal on the line 772 to the summer 770 is stator offset, which is calculated in block 774 based on the four mentioned input parameters. The remainder of Fig. 20 is analogous to the remainder of Fig. 4 and the above discussion in the "(A) System Overview" section is applicable.

Fig. 21 which calculates the rotor displacement of the low pressure turbine will be compared with Fig. 5 which calculates the rotor displacement of the high pressure turbine. Block 771 in Fig. 21 calculates blade heat displacement, which is the elongation of the turbine blades due to temperature changes. The input signal on line 772 is blade temperature, which will be at or near the temperature of the low pressure turbine inlet, which is the measured parameter on line 772. The calculation of blade temperature is simpler than the calculation made for block 192 in Fig. 5 due to Fig. 5 the blade temperature is a function both of cooling air and of see combustion gases hitting the blades. No such cooling takes place for the low-pressure turbine blades in the preferred embodiment, so that the calculation in Fig. 21 is simpler. If blade cooling is used, however, the calculation in Fig. 5 can be used.

Based on four parameters, namely fan speed, cavity temperature 757 in Fig. 1A, which contains the low pressure turbine, low pressure turbine inlet pressure, and low pressure turbine inlet temperature, block 775 in Fig. 21 calculates the following: hub and edge temperature, (corresponding to the holes) and life in Fig. 35), on line 777, and the hub and edge displacement based on the temperatures. Ü 468 059 The temperature on line 777 is used by block 780 to calculate the modulus of elasticity of the rotor material. Furthermore, block 782 calculates the change in the modulus of elasticity of the turbine blades. These module changes are added to the summer 785, which feeds the multiplier 788, which multiplies the sum of the core speeds squared on line 790. The multiplier 788 performs a similar function as the multiplier 173 in Fig. 5.

A calculation of the modulus of elasticity of the turbine blades takes place in Fig. 21, but does not take place in Fig. 5 for the high-pressure turbine. One reason is that the low-pressure blades are much longer than the high-pressure turbine blades, which is why the elongation of the blades due to centrifugal force is greater than in the case of the high-pressure turbine.

The centrifugal displacement from the multiplier 788 is added to the heat displacement of the blade from the block 771 in the summer 793, and a signal is emitted on line 795, which is a signal (RRD) indicating rapid rotor displacement, as in Fig. 5. The signal is called rapid rotor displacement because the displacement occurs almost instantaneously as the rotor contract increases: centrifugal displacement is instantaneous, and the turbine blades follow the temperature of those entering the turbine so fast that the blade heat growth, calculated in block 770, can be considered almost instantaneous.

Rapid rotor displacement is added in the summer 798 to the heat displacement of the disc, which gives the actual displacement of the whole rotor on line 800, which line is also shown in Fig. 20. The calculation of block 775 in Fig. 21 will now be touched upon.

The operation of a similar block 209 in Fig. 6 is explained in the above discussion under the heading "(B) High pressure turbine rotor displacement, overview (Fig. 6)". Similar to the high pressure turbine situation shown in Fig. 7, two time constants (in blocks 865 and 868) are used in Fig. 23 for the low pressure disk, one for an edge region and one for a hub region. For the low pressure turbine, the hub area is considered to end at point 3180 in Fig. 35, which is at a value of ______ on a scale of 0 to 100 in the figure, as opposed to the end point of the hole for the high pressure turbine, which is at a value of 40 units, as indicated above.

As in Fig. 7 for the high pressure turbine, a power parameter is calculated in Fig. 23 on line 850, similar to line 246 in Fig. 7, and the power parameter is your indicator of the insulating capacity (or reverse thermal conductivity) of the pressurized air around the board. Dense, hot high pressure air, at a high temperature as indicated by the parameters on lines 853 and 856, will, for example, strive to heat the disc faster when the fan speed on line 859 is high due to the relative movement between the disc and the air producing an scrubbing effect. which facilitates heat transfer. The output of block 862 in Fig. 23 is a pair of modifiers, one for each time constant on the disk, which are included in blocks 865 and 868. As discussed above in connection with the high pressure turbine, the heat transfer model used assumes a second order system with two time constants, namely a fast time constant and a slow time constant. The time constant is blocks 865 and 868 for the low pressure turbine are analogous to the time constants in blocks 250 and 252 in Fig. 7 for the high pressure turbine.

Block 820 in Fig. 22 calculates the stationary temperature of the turbine disk 758 (ie for both hub and edge) in Fig. 1A, which will be achieved if the operating conditions specified by the parameters on input lines 880 remain. Fig. 24 shows the calculation of the hub and edge temperatures in the steady state in more detail.

The edge temperature is affected not only by the temperature of the air in the cavity 757 in Fig. 1A, but also by the heat flow from the turbine blades hitting the air. The edge temperature in the stationary state is thus affected by signals on both lines 892 and 894 in Fig. 24. Block 887 provides a factor to the multiplier 890 which indicates the efficiency of the heat transfer due to the scrubbing action between the air in the cavity 757 and the disk 758, and this factor is a function of the fan speed. Block 887 also provides a factor to multiplier 884, which indicates the heat flow rate from the turbine gases to the edge. On the other hand, the hub temperature is mainly affected by the temperature of the cavity, and the block 901 thus provides a signal to the multiplier 898, which indicates the efficiency of the heat transfer between the cavity air and the hub.

The steady state temperature of both the hub and the edge, calculated in Fig. 24 together with two time constants for each, from blocks 865 and 868 in Fig. 23, is fed to the delay network 825 in Fig. 22, which is shown in Fig. 32 and which is identical to that shown in Figs. 7 and 15 and explained under the heading "(G) Temperature delay network (Fig. 15)" above.

The output of the delay network 825 in Fig. 22 is supplied to the disk offset block 830 if the status indicator 827 indicates that the engine is running. The status indicator indicates that the engine is not running, block 830 calculates the disc temperature in the same way as described in Fig. 9, in the section entitled "(B) (1) (ii) High pressure turbine disc temperature, engine not running (Fig. 6 and 9). " Either the motor is running or not, block 830 calculates the displacement of the disk and is shown in more detail in Fig. 25. The operation of Fig. 25 is similar to that of Fig. 8, except for the use of various constants, such as KLPCT2. The procedure of Fig. 8 is described in the above section entitled "(B) (l) Heat Shift of the High Pressure Turbine Board (Fig. 6)".

The foregoing discussion has explained how the displacement of the low pressure motor, on line 800 in Fig. 21, is calculated. This discussion will now consider the calculation of the displacement of the low pressure housing.

In Fig. 26, the heat displacement of the housing, on line 940, is added to the displacement, on line 943, which is caused by pressure within the housing. In general, the pressure offset is a linear function of the inlet pressure of the low pressure turbine and thus the multiplication of this pressure with the constant in block 947 allows calculation of the pressure offset.

The heat displacement is calculated as shown in Figs. 27-30. In Fig. 27, block 970 calculates the two time constants of the casing based on the core air flow and cooling air flow. The time constants are used by block 973 which calculates actual transient temperature, which is sent to block 976, which uses the calculated temperature to calculate actual envelope displacement. Block 970 is shown in more detail in Fig. 28.

The time constants in blocks 1002 and 1004 have the nominal values given in Fig. 34. Each time constant is modified in Fig. 28 by both core flow and cooling air flow, for similar reasons as the time constants in blocks 398 and 401 in Fig. 12 are modified by the core flow.

Both time constants in blocks 1002 and 1004 are multiplied by the core flow modifier in block 1022 to generate a pair of first time constant products (TC), from multipliers 1008 and 1010.

Another pair of constants, in blocks 1014 and 1018, are each multiplied by a cooling flow modifier in block 1024 to provide a pair of other TC products, derived from multipliers 1030 and 1032. One of the other TC products, from multiplier 1032, is added in summer 1012 with one of the first TC products, namely from multiplier 1010. The second TC product is added to the second first TC product in summer 1028. In this way, each time constant is affected by both core air flow and cooling air flow for similar reasons as stated above. for the time constants in blocks 398 and 401 in Fig. 12.

The operation of the delay network 1050 in Fig. 29, shown in more detail in Fig. 32, is substantially identical to that in Fig. 15 for the high pressure turbine and the discussion above under the section entitled "G" Temperature Delay Network (Fig. 15) "explains the mode of operation. The output of the delay network 50 in Fig. 29 indicates the actual temperature of the housing 744 in Fig. 1A 468 059 32 and is fed to the block 976 in Fig. 27, which is shown in more detail in Fig. 30. the method of Fig. 30 is substantially identical to that of Fig. 13, if one realizes that the block 1080 in Fig. 30 is indicated by the dashed block 507 in Fig. 13. The discussion above in the section entitled "(E)" The high pressure turbine casing displacement (Fig. 13) "explains the calculation of the heat displacement of the casing in Fig. 30.

The previous discussion has explained how the casing displacement has been calculated based on two components, which include displacement, namely pressure displacement and heat displacement.

The calculations in Figs. 29, 31 and 33 are substantially identical to those of Figs. 12, 14 and 18. The dynamic block block valve 776 in Fig. 20 is further identical to that in Fig. 4, so that the previous discussion is also applicable. here.

Several significant features of the invention are as follows. First, in Figs. 19 and 34, constants are used which are used for the calculations given in the other figures.

Second, the use of a delay network such as 266 in Fig. 7 causes the calculated temperature of a component, such as a housing or rotor, to mimic the actual component temperature during transient processes. Accordingly, the squeezing conditions that might otherwise occur, as described in the background of the invention, are substantially reduced or eliminated. One reason is that the imitation provides accurate information regarding the size of the component, which allows the control system to know when a pinch condition may occur, and to terminate or reduce the shrinkage of the housing as a result.

Third, it should be noted that Figures 4 to 34 indicate an embodiment of the invention, and in flow chart form. The flowchart represents a computer program for use in a programmable digital computer. The program can of course be applied in another way, such as in an analog computer, or in a non-programmable digital computer.

Fourth, the invention estimates the present instantaneous temperature of an engine component, such as a rotor or casing, based on the changes in the steady state temperature predicted to be achieved by the component when the engine reaches steady state during the present operating condition. The time dependence of the predicted temperature in the steady state thus allows determination of the present instantaneous temperature of the component.

It will be appreciated that since the steady state temperature is calculated from selected motor operating conditions, such as those fed to blocks 107 and 126 in Fig. 4, the instantaneous temperature can be calculated directly from changes in operating conditions. one can calculate the instantaneous temperature directly from changes in operating conditions. Fifth, the invention can be considered as containing a mathematical mode 11 of the rotors and heights by the ability to calculate the temperature in the stationary state and the eye temperature of the rotors and heights.

The mode provides the temperatures, and thus the dimensions, of these components in different engine operating conditions. Furthermore, the mode interpolates between dimensions, with a time delay added when the operating condition changes.

Sixth, delay networks, such as network 266 in Fig. 7, have been discussed. The delay network causes an output variable on line 268 to follow an input variable on line 270. The variable is subjected to a delay. When input variables jump from one value to another, for example, output variables are limited to approaching, almost asymptotically, output variables, at a rate determined by the relevant time constant.

Claims (18)

468 059 34 Patent claims. A clearance control device in a gas turbine engine comprising a rotor and a surrounding housing, and comprising means for regulating the temperature of the housing for the purpose of achieving the desired clearance between the rotor and the housing, and means (101) for calculating a desired clearance between the rotor and the housing based on engine speed, characterized by means (107,126) for calculating rotor and housing displacements based on measurements of selected engine operating characteristics, and means (120) for combining the desired clearance with the calculated rotor and housing displacements for determine a clearance error, whereby the correct setting of the casing temperature is achieved to achieve the desired clearance. (Fig. 4). The apparatus of claim 1, wherein said means for controlling the casing temperature comprises a source of compressed air and a valve for regulating the flow of compressed air to the casing, characterized by means (138) for calculating the amount of air flow available to control the casing. temperature. (Fig. 4). Device according to claim 1, wherein the rotor comprises a disc and a plurality of blades extending radially outwards from the disc, characterized in that said means (107) for calculating the motor displacement comprises means (209) for calculating the heat displacement of the disc. means (192) for calculating the heat displacement of the blades, means (173,176) for determining the centrifugal displacement of the rotor, means (179) for summing the heat displacement of the blades and centrifugal displacement for determining a rapid rotor displacement, and means (202) for calculating sum the fast rotor displacement and the heat displacement of the disc to determine a total rotor displacement. (Fig. 5). Device according to claim 3, characterized in that the means for calculating the heat displacement of the disc comprise: means (218) for providing a first signal (268), which is indicative of the temperature of the disc based on selected motor operating conditions; means (222) for providing a second signal (220) indicative of the temperature of the disk when the engine is not running; and means (212) for selecting the first signal to calculate the heat displacement of the disk when the engine is running and for selecting the second signal to calculate when the engine is not running. (Fig. 6). An apparatus according to claim 4, wherein the gas turbine engine comprises an air compressor, characterized in that the means for producing a first signal comprises means for predicting stationary disk temperatures based on selected present operating conditions, including temperatures of the disk hole and web; means for searching engine speed, compressor outlet pressure and temperature for modifying time constants relative to heat transients, a delay network (266) for receiving the stationary temperatures and the transient time constants for both the life and the hole and emitting an output signal based on either the stationary temperature or the transient temperature depending on the engine operating conditions. (Fig. 7). Device according to claim 5, characterized in that the delay network comprises: a first delay circuit (580,583,586,589,598), which receives the stationary temperature input signal and modifies the temperature with a first time constant to generate a first delayed output temperature; a hinge circuit (618) which receives the stationary temperature signal and includes multipliers to allow the stationary temperature to dominate the first delay output temperature and provide an output signal from the phase shift circuit; and a second delay circuit (579) connected to receive the output signal from the hinge circuit to apply a second time constant different from the time constant of the first delay circuit, whereupon the output signal is the same as the stationary input signal under stationary state or follows the stationary the input signal with a time delay under transient conditions depending on acceleration or deceleration. (Fig. 15). 36 Device according to claim 4, wherein the disc comprises hollow and life parts, and the gas turbine engine comprises an air compressor, characterized in that the means for providing a second signal indicating the temperature of the disc when the engine is not running comprise: means for selecting a fault temperature or a calculated temperature based on the identity of the engine; and when there is an identity between the engine and the previous operation, means for calculating the hole and life temperatures after switch-off according to the expression: Temp = -from time / time art. (Tgammal "Tref) fe 1 'Tref' (fig '9). Device according to claim 4, wherein the disc consists of a web part and a hole part, characterized in that the means for calculating the heat displacement of the disc comprise: means for receiving one of the first or second selected signals related to disc temperature, comprising separate hole and web temperatures ; means for determining coefficients of thermal expansion based on the intemperature signals related to hole and life temperatures; means for multiplying the coefficients of thermal expansion by holes resp. the lifetimes and the deviation of the temperature signals to determine the elongation of each of the holes and life; and means for combining each of the life and hole extensions to determine a heat displacement of the disc. (Fig. 8). Apparatus according to claim 1, characterized in that the means for calculating casing displacements comprise means for determining the total displacement of the casing, comprising: means for determining the thermal displacement of the casing; means for determining the pressure displacement of the housing; means for determining the displacement of the casing support; and a summator (326) for combining the heat, pressure and support displacements of the casing to determine the total casing displacement. (Fig. 10). Apparatus according to claim 9, characterized in that the means for determining the displacement of the casing comprise: means (393) for calculating at least one time constant 37 468 059 based on nuclear air flow; means for calculating a stationary temperature of the housing based on combined fan and compressor outlet air flow temperatures modified by the heat transfer capacity of the housing based on the amount of cooling air flow; and a delay network (266) for combining the stationary temperature of the housing and the time constant for calculating a transient temperature for the housing. (Fig. 12). Device according to claim 9, characterized in that the means for determining the heat transfer of the casing comprise: means (498) for multiplying the difference between the transient temperature of the casing and the room temperature by the coefficients of thermal expansion at the transient temperature of the casing and the size of the casing at room temperature to determine a heat displacement at the housing. (Fig. 13). Apparatus according to claim 2, characterized in that the means for calculating the amount of air flow available to control the temperature and the housing comprise: means (531) for determining the maximum available cooling lift flow; means for determining a corrected valve setting; and means for multiplying the maximum air flow by the corrected valve setting. (Fig. 14). Device according to claim 2, comprising means for regulating the valve based on the accuracy of selected motor sensors, characterized by: means for determining the accuracy of selected motor sensors and providing a signal based on whether the sensors are in operation or not in operation; switch means driven by said accuracy determining means; a first switch input signal constituting an overload signal, whereby the valve will be driven to a fail-safe or closed valve position when the sensors are determined to be out of order; and a second switch input signal based on the clearance error signal, whereby the valve will be operated in accordance with the calculated error signal, when it is determined that the sensors are in operation. (Fig. 16). 468 059 38 The device of claim 1, wherein the rotor comprises a disk member having a plurality of blades extending radially outwardly therefrom, characterized in that the means for calculating a desired clearance comprises: means for determining a stationary clearance signal based on actual motor speed; means for determining a rapid motor displacement signal based on the heat displacement of the blades combined with the centrifugal displacement of the rotor disk; means for selecting the larger of the stationary or fast rotor displacement signals as the new desired clearance signal. (Fig. 18). Device according to claim 14, characterized by means for dividing the fast rotor displacement signal into steps according to a preselected constant rate after an acceleration so that the fast rotor displacement signal will be adapted to the stationary clearance signal. (Fig. 18). Device according to Claim 1, characterized in that the rotor growth calculations and the calculations of the desired clearance are based on the engine speed input signal. Device according to Claim 1 for a high-pressure gas turbine, characterized in that the engine speed is the actual core speed. Device according to Claim 16 for a low-pressure gas turbine, characterized in that the engine speed is the fan speed.